As an alumnus of Newsweek and Time in their glory days, I sometimes can’t resist thinking like a news-magazine editor. Any news event -- the government shutdown, the withdrawal from Syria, the Brexit mess -- can be summarized by that all-purpose cover line, “NOW FOR THE HARD PART.”

Similarly, the obvious cover for next Monday would be a racetrack starting gate with more than a dozen familiar Democrats (“There’s Bernie, there’s Beto, there’s Biden, there’s Booker ... ”) leaning forward in their saddles as the cliche-ridden headline proclaims, “AND THEY’RE OFF.”

A quarter century ago, Bill Clinton could wait until Oct. 3, 1991, to declare his 1992 candidacy and Mario Cuomo (the father of current New York Gov. Andrew Cuomo) could play Hamlet on the Hudson until he deliberately missed the late December filing deadline for the New Hampshire primary.

But such languor is now as outdated as, well, news magazines shaping the political discourse.

The Democratic National Committee has already scheduled the first primary debates for June and July 2019. And a front-loaded primary calendar (California and Texas will dominate a souped-up Super Tuesday on March 3, 2020) means that presidential contenders may need to raise as much as $200,000 a day all through 2019, which provides additional motivation for an early start.

Despite the premature fixation on early polls, it is impossible to game out the Democratic race this far in advance.

This applies to candidates as well as pundits. Mike Bloomberg, for example, has been telling anyone in earshot that he will only run if he thinks he can win. But what’s the former New York mayor’s tolerance for risk? Does he demand a 50 percent shot (unattainable no matter how much money he spends), a 15 percent chance (which seems overly optimistic) or a probably realistic 5 percent possibility?

Even what we think we know about primary politics has been upended by the Democratic Party’s new rules. Take as an illustration the opening-gun Iowa caucuses, scheduled for Feb. 3, 2020.

In prior years, the problem with handicapping the Iowa caucuses has been predicting who would show up in person to vote on a cold mid-winter Monday night. The assumption has always been that -- unlike a primary -- Iowa measures the enthusiasm of activists.

But party rules will now allow for absentee balloting at the caucuses. Does that argue that the participation will be even greater than the 240,000 Iowa Democrats who powered insurgent Barack Obama to victory in 2008? Does that mean that the caucus electorate will not tilt as far left (Bernie Sanders almost beat Hillary Clinton in 2016) as in prior years?

The adage about the role of the caucuses in winnowing the Democratic field has always been, “There are three tickets out of Iowa.” But this time around, there could be eight or even more tickets out of Iowa. The reason: Another little-noticed change in Democratic rules.

Until now, due to a quirk in caucus procedures, a Democratic candidate needed 15 percent support in any precinct to have his or her votes tallied at all. But in 2020, Iowa caucus votes will be counted just like they are in primaries. As a result, it is easy to envision a cluttered Iowa result with, say, a half-dozen candidates clustered around 8 percent.

When it comes to winning a presidential nomination, the devil is often in details like these. Had, for example, Hillary Clinton vigorously contested the 2008 caucuses scheduled after Iowa -- in which Obama romped almost unopposed -- a different Democratic president probably would have moved into the Oval Office in 2009.

The 2020 nomination fight will be the first Democratic contest since 1980 that will not be shaped by either Ronald Reagan or opposition to George W. Bush’s Iraq War.

The political caution of the Clintons (who ran in 1992, 1996, 2008 and 2016) was a nervous response to witnessing three GOP presidential landslides in the 1980s. The Al Gore of 2000 (who played down his environmental passions) also fit into this centrist mold.

As for the Iraq War, it was responsible for the stunning 2003 rise of Howard Dean, America’s first internet-powered candidate. (Dean’s Icarus-like 2004 collapse was because of other factors). And in 2008, early opposition to Bush’s war gave Obama his initial rationale to challenge the hawkish Hillary.

Donald Trump, of course, has made the presidencies of Ronald Reagan and George W. Bush seem almost as distant as William McKinley’s “front-porch campaign” of 1896.

For some activists, the final break with the Clinton and Obama years means that 2020 candidates should be assessed for political purity. Any deviation on left-wing litmus-test issues like Medicare for all or a Green New Deal is a reason for scorn. Even more heretical is any history of accepting support from Wall Street Democrats or the oil and gas industry.

From my perspective, this rigidly ideological approach is misguided. What America, and not just the Democrats, need most of all in 2020 is a presidential candidate who can begin to heal the nation’s deep wounds.

Part of the package would be an inspirational appeal to our better angels as citizens. But even more important would be that half-forgotten virtue called competence -- the ability to understand how government works and to know how to use the levers of power to recover from the wreckage of the Trump years.

It used to be said derisively about political incompetents, “He could screw up a one-car funeral.” Trump made presidential history this week by screwing up a Christmas Eve photo-op, mocking a 7-year-old girl’s belief in Santa Claus.

By this standard, any Democrat (and any rational Republican) would offer a dramatic improvement over Trump. But the trick will be to find the best man or woman to transcend the guttersnipe politics and know-nothing governing style that has, tragically, become the 2018 norm.

Walter ShapiroWalter Shapiro is an American journalist, writer and columnist. -- Ed.